Sub-miniature selector device with eccentrically displaced contact wiper apparatus



July 19, 1966 G. J. NEFF, JR 3,261,929

SUB-MINIATURE SELECTOR DEVICE WITH ECGENTRICALLY DISPLACED CONTACT WIPER APPARATUS Filed Feb. 17, 1964 2 Sheets-Sheet l l2 6 IO -5o 26 44 ll|||l I 4|] 58 INVENTOR 56 GEORGE J. NEFEJR. I

ATTORNEYS.

July 19, 1966 G. J. NEFF, JR 3,251,929

SUB-MINIATURE SELECTOR DEVICE WITH ECCENTRICALLY DISPLACED CONTACT WIPER APPARATUS Filed Feb. 17, 1964 2 Sheets-Sheet 2 ATTORNEYS.

GEORGE J. NEFF,

United States Patent SUB-MINIATURE SELECTOR DEVICE WITH ECCENTRICALLY DISPLACED CONTACT WIPER APPARATUS George J. Nelr, Jr., Erlanger, Ky., assignor to Avco Corporation, Cincinnati, Ohio, a corporation of Delaware Filed Feb. 17, 1964, Ser. No. 345,259 6 Claims. (Cl. 200-11) This invention relates to a unique multiposition switch in combination with printed circuit parameters constructed in sub-miniature form.

The present invention provides means for the construction of sub-miniature electric circuit printed parameters and for the selection of particular parameters by the positioning of a unique rotor assembly. Briefly described, circuit para-meters are deposited, or otherwise printed, on a ceramic substrate wafer along with a plurality of contacts printed in two concentric arcuate paths surrounding a circular aperture in the wafer. A circular Spring contact element, supported on an elongated carrier and eccentrically mounted with respect to the aperture, serves simultaneously to brush the two arcuate paths to select particular output points for connection in other circuitry. The printed circuits may be resistors, capacitors, inductors, or any other parameter adaptable to printed circuit techniques.

his the primary object of this invention to provide a wafer having circuit parameters printed thereon and on which printed contacts are positioned in concentric arcuate paths around a circular aperture in the wafer, and to provide a rotatable circular spring contact eccentrically positioned with respect to the aperture.

Another object of this invention is to provide a rotatable circular spring member curved along one of its diameters to provide contact points at the ends of said diameter, said' circular contact being eccentrically positioned with respect to its axis of rotation for simultaneously contacting two concentric paths of contacts.

Another object of this invention is to provide a unique contact element comprising a circular spring member curved along one of its diameters and carried between the ends of an elongated contact carrier element, said carrier being rotatably mounted, said spring-contact element being eccentrically mounted with respect to the axis of rotation of the carrier.

For further objects and for a better understanding of the invention, reference should be made to the following detailed specification and to the accompanying drawings in which:

. FIGURES 1 and 2 illustrate a typical embodiment of this invention;

FIGURES 3 and 4 are views of the contact and carrier of FIGURES 1 and 2;

FIGURES 5 and 6 are views of a modified contact and carrier; and

FIGURE 7 illustrates the assembly for the modified spring contact in captive and self-aligning relationship with respect to the contacts printed on the wafer.

Referring to the drawings, the apparatus includes a ceramic substrate wafer 10 formed with a circular apertur'e 12 through which extends a shaft 14 rotatably supported coaxially with the aperture 12 in end plates 11 and 13. The substrate wafer 10, serving as the stator, is formed with a plurality of trenches and cavities into which various circuit elements are deposited and fired-in, or otherwise printed. These circuit elements include an annular collector ring 16 concentrically positioned around the aperture 12. A deposited lead 18 connects the ring 16 to a deposited common terminal 20. concentrically surrounding the collector ring 16 are a plurality of printed contacts 22, each one of which is connected by a short printed lead 24 to a respective one of a plurality of resistance elements 26. The resistance elements 26 are interconnected by means of short printed leads 28 to provide a series string, the end elements of which are connected by means of printed leads 30 and 32 to terminals 34 and 36, respectively.

In this embodiment, the remaining terminals 37 are dummies, but are available for other circuit configurations. For example, the leads 24 might be eliminated, and each resistor might be independently connected to a respective one of the terminals.

The various resistor elements 26 are overlaid with a nonconductive spacer 38 'aflixed to the wafer 10.

A rotor assembly 41, including an appropriately apertured contact carrier 42 keyed to the shaft 14, is positioned Within the circular recess formed by the spacer 38 and the wafer 10. The contact carrier 42. is made of very thin nonconducting material and is provided'for supporting a spring contact 44 of generally circular configuration mounted eccentrically with respect to the axis of the shaft 14 in grooves provided at the ends of the contact carrier 42. The spring contact is maintained in position by an epoxy 45 deposited in the grooves, and is curved or bent downwardly along one of its diameters towards the wafer and provided with dimples 46 and 48 at the points Where the spring makes contact with the wafer 10. Since the spring contact 44 is mounted eccentrically with respect to the rotor shaft, the dimple 46 brushes a circular path of one diameter which includes the contacts 22, while the dimple 48 brushes the smaller diameter path of the collector ring 16. Thus, as the shaft 14 is rotated in either direction, the dimple 48 selects a particular contact 22 for connection to the common terminal 20 through the lead 18, the collector ring 16, and the spring contact 44.

While the carrier 42 is angularly fixed with respect to the shaft 14, the tolerances are such that it is axially movable on the shaft. Thus, when additional units, such as illustrated in dashed lines, are stacked on the shaft 14, the rotor assembly, including the carrier 42 and the spring contact 44, is maintained in position, with the spring contact dimples properly aligned and maintained under pressure with the printed collector ring 16 and contacts 22 by the reaction of the spring contact 44 with the bottom of the upper unit 50.

Because of the very small size of the apparatus, it is necessary that each of the elements be small, and yet it is required that the contact dimples 46 and 48 be maintained under pressure with the wafer contact elements. To accomplish this, the spring contact 44 was made circular in cross section, and two beneficial results were achieved. First, the distance between the grooves on the carrier 42 for supporting the contact were spaced widely apart, thereby reducing the probability of weakening the center of the carrier. Second, the circular configuration permitted the maximum spring pressure for a contact of given radius from the shaft axis.

The modified embodiment of this invention illustrated in FIGURES 5-7 uses an assembly in which the elements of the rotor 51 are self-contained on the wafer. In this embodiment a modified contact carrier 52 is provided at each end with peripheral arcuate flanges 54, both constituting arcs of the same circle having a center at the axis of shaft 14. When the contact carrier with its spring contact 44 is positioned on the wafer 10, it is overlaid with a nonconductive spacer 56 having a complementary circular flange 58 overlying the flange 54 and providing a raceway for it. Thus, the flanged spacer 56 permanently maintains the rotor 51 in position on the wafer 10. A plurality of such assemblies may be stacked in the same manner as illustrated in FIGURE 2.

The structures of both embodiments of this invention are particularly suited for use in connection with thin film parameters in printed circuits such as illustrated. However, the principles apply broadly to any type of electronic circuitry and to the switching of the circuits and parameters in such circuitry. The illustrated embodiments comprise simple potentiometers in which printed resistor elements are connected in series and a particular output point is selected. Obviously, the device may be used in selecting independent resistors, each connected to a respective one of the terminals 34, 36 and 37 or each connected to a single one of the terminals. Moreover, it is well within the skill of the art to substitute other printed parameters such as capacitors, inductors, and solid-state devices. Any parameter which may be fabricated in subminiature or thin-film technique may be made the selected element of this miniature device. In practice, a wafer approximately one inch square and aproximately .02 inch thick was used for a -element unit such as illustrated. The contact carrier is approximately .04 inch thick. The illustrated embodiments disclose single-pole, multi-position selector elements. However, the invention need not be so limited since each section may be multi-poled and each may be provided with 360-degree rotation or less as the instant problem demands.

It is apparent, therefore, that many modifications and adaptations of this invention will be apparent to persons skilled in the art, and accordingly this invention should be limited only by the appended claims as interpreted in the light of the prior art.

What is claimed is:

l. The combination comprising:

a thin wafer of insulating material having an aperture therethrough;

a shaft rotatable on an axis extending through said aperture;

printed electrical circuitry on one surface of said wafer, said circuitry including first and second annular races of printed contacts, said races being positioned concentrically with the axis of said shaft and having first and second diameters, respectively;

a nonconductive spacer overlying and aflixed to said surface of said wafer, said spacer having a circular aperture with a diameter at least as great as the greater of said two races, whereby said races are exposed in a circular recess defined by the circular aperture of said spacer;

an elongated contact carrier positioned within said recess, the ends of said elongated contact carrier comprising the arcs of a circle having a diameter slightly less than the diameter of said recess, said contact carrier being angularly fixed to said shaft but axially movable thereon;

a substantially circular spring contact bridging and fixedly supported from between the ends of said carrier, said spring contact being curved along one of its diameters toward and into contact with said surface, said diameter of said spring contact intersecting the axis of said shaft at a point spaced from the center of the spring contact, the diameter of the spring contact being dimensioned so that one end thereof is at a distance from said axis equal to the radius of one of said races and the other end thereof is at a distance from said axis equal to the other of said races; and

means for axially confining and urging said circular spring contact against said races, said last-named means comprising an inwardly extending flange on said spacer, said flange being spaced from said surface and overlying said carrier for providing an annular raceway for said carrier.

2. The invention as defined in claim 1 wherein said carrier is provided with flanges at said arcs complementary to the flange of said spacer.

3. The invention as defined in claim 2 wherein said printed circuitry comprises conductive contacts.

4. The invention as defined in claim 3 wherein one of said races comprises a continuous circular conductor.

5. The invention as defined in claim 4 wherein the 0 other race comprises a plurality of contacts.

6. The combination comprising:

a thin wafer of insulating material having an aperture therethrough;

a shaft rotatable on an axis extending through said aperture;

printed electrical circuitry on one surface of said wafer, said circuitry including first and second annular races of printed contacts, said races being positioned concentrically with the axis of said shaft and having first and second diameters, respectively;

a nonconductive spacer overlying and affixed to said surface of said wafer, said spacer having a circular aperture with a diameter at least as great as the greater of said two races, whereby said races are exposed in a circular recess defined by the circular aperture of said spacer;

an elongated contact carrier positioned within said recess, the ends of said elongated contact carrier comprising the arcs of a circle having a diameter slightly less than the diameter of said recess, said contact carrier being angularly fixed to said shaft but axially movable thereon;

a substantially circular spring contact bridging and fixedly supported from between the ends of said carrier, said spring contact being curved along one of its diameters toward and into contact with said surface, said diameter of said spring contact intersecting the axis of said shaft at a point spaced from the center of the spring contact, the diameter of the spring contact :being dimensioned so that one end thereof is at a distance from said axis equal to the radius of one of said races and the other end thereof is at a distance from said axis equal to the other of said races; and

means for axially confining and urging said circular spring contact against said races.

References Cited by the Examiner t UNITED STATES PATENTS ROBERT K. SCHAEFER, Primary Examiner.

KATHLEEN H. CLAFFY, ROBERT S. MACON,

Examiners. J. R. SCOTT, Assistant Examiner. 

1. THE COMBINATION COMPRISING: A THIN WAFER OF INSULATING MATERIAL HAVING AN APERTURE THERETHROUGH; A SHAFT ROTATABLE ON AN AXIS EXTENDING THROUGH SAID APERTURE; PRINTED ELECTRICAL CIRCUITRY ON ONE SURFACE OF SAID WAFER, SAID CIRCUITRY INCLUDING FIRST AND SECOND ANNULAR RACES OF PRINTED CONTACTS, SAID RACES BEING POSITIONED CONCENTRICALLY WITH THE AXIS OF SAID SHAFT AND HAVING FIRST AND SECOND DIAMETERS, RESPECTIVELY; A NONCONDUCTIVE SPACER OVERLYING AND AFFIXED TO SAID SURFACE OF SAID WAFER, SAID SPACER HAVING A CIRCULAR APERTURE WITH A DIAMETER AT LEAST AS GREAT AS THE GREATER OF SAID TWO RACES, WHEREBY SAID RACES ARE EXPOSED IN A CIRCULAR RECESS DEFINED BY THE CIRCULAR APERTURE OF SAID SPACER; AN ELONGATED CONTACT CARRIER POSITIONED WITHIN SAID RECESS, THE ENDS OF SAID ELONGATED CONTACT CARRIER COMPRISING THE ARCS OF A CIRCLE HAVING A DIAMETER SLIGHTLY LESS THAN THE DIAMETER OF SAID RECESS, SAID CONTACT CARRIER BEING ANGULARLY FIXED TO SAID SHAFT BUT AXIALLY MOVABLE THEREON; A SUBSTANTIALLY CIRCULAR SPRING CONTACT BRIDGING AND FIXEDLY SUPPORTED FROM BETWEEN THE ENDS OF SAID CARRIER, SAID SPRING CONTACT BEING CURVED ALONG ONE OF ITS DIAMETERS TOWARD AND INTO CONTACT WITH SAID SURFACE, SAID DIAMETER OF SAID SPRING CONTACT INTERSECTING THE AXIS OF SAID SHAFT AT A POINT SPACED FROM THE CENTER OF THE SPRING CONTACT, THE DIAMETER OF THE SPRING CONTACT BEING DIMENSIONED SO THAT ONE END THEREOF IS AT A DISTANCE FROM SAID AXIS EQUAL TO THE RADIUS OF ONE OF SAID RACES AND THE OTHER END THEREOF IS AT A DISTANCE FROM SAID AXIS EQUAL TO THE OTHER OF SAID RACES; AND MEANS FOR AXIALLY CONFINING AND URGING SAID CIRCULAR SPRING CONTACT AGAINST SAID RACES, SAID LAST-NAMED MEANS COMPRISING AN INWARDLY EXTENDING FLANGE ON SAID SPACER, SAID FLANGE BEING SPACED FROM SAID SURFACE AND OVERLYING SAID CARRIER FOR PROVIDING AN ANNULAR RACEWAY FOR SAID CARRIER. 